20 Tra7isactions. 



tains this direction for twenty-four or thirty-six hours, the advent of an 

 antarctic depression is portended. 



Sometimes when the lowest pressure of an antarctic " low " has passed 

 the meridian of the Bluff great cirrus plumes, moving fast, appear to the 

 S. or S.S.W. : the barometer then rises slowly, and later very rapidly, a 

 southerly storm following up the east coast of the South Island. If the 

 rise of the barometer is due to the advent of the anticyclone following in 

 rear of the antarctic system, the " southerly " usually extends to the lati 

 tude of East Cape, and a rough sea makes into the Bay of Plenty. 



These westerly wave-pressures are usually most pronounced in the 

 spring of the year, and they have been very fully described by Captain 

 Edwin in the Transactions. 



Occasionally cirrus, frequently striated, is seen moving very rapidly 

 from the N.W. : a change in the weather then occurs shortly, winds from 

 between N.E. and B., and heavy rain on the northern coastal districts. 



Art. III. — Harmonic Tidal Constants of New Zealand Ports — Wellington 



and Auckland. 



By C. E. Adams, M.Sc, F.R.A.S., Government Astronomer of New Zealand. 



[Read before the Wellington Philosophical Society, 23rd October, 19 12. 'I 



The harmonic tidal constants given in culimns (1) and (4) of the attached 

 schedule were obtained from an harmonic analysis of the hourly ordinates 

 from the automatic tide-gauges at WelHngton and Auckland. For each 

 port the tidal abacus of Sir G. H. Darwin was used, and the whole of 

 the calculation has been carried out in duplicate. For the additions the 

 Mercedes adding-machine has been found to be of the greatest assistance, 

 while the Brunsviga calculating-machine, with printing attachment, and 

 the Millionaire calculating-machine have been invaluable in the numerous 

 calculations. For the fine plotting of curves the Coradi co-ordinatograph 

 has been very useful. 



From the constants given in columns (1) and (4) the tides for Welling- 

 ton and Auckland have been predicted, and are published in the " British 

 Admiralty Tide-tables " and in the " New Zealand Nautical Almanac." 

 Comparisons between the predictions and actuality prove the correctness 

 of the constants. For these comparisons see New Zealand Tidal Survey : 

 Report of Department of Lands and Survey, Wellington, 1910-11 and 

 1911-12. 



Other values of the tidal constants — (1) by the United States Coast 

 and Geodetic Survey, and (2) by Mr. T. Wright — are given in columns (2) 

 and (5) and (3) and (6) respectively. 



